• The Transactions of the Korea Information Processing Society
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• v.7 no.8
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• pp.2421-2429
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• 2000

With the advance of wireless communications technology, mobile communications have become more convenient than ever. Nowadays, people can communicate with each other on any place at any time. However, because of the openness of wireless communications, the way to protect the privacy between communicating parties is becoming a very important issue. In this paper, we present a study on the authentication and message encryption algorithm to support roaming service to the GSM network. To propose an authentication and message encryption algorithm applicable to the GSM system, the security architecture of the GSM outlined in the GSM standard is briefly introduced. In the proposed cryptosystems we use a new hash function for user authentication and a stream cipher based on Linear Feedback Shift Register(LFSR) for message encryption and decryption. Moreover, each algorithm is programmed with C language and simulated on IBM-PC system and we analyze the randomness properties of the proposed algorithms by using statistical tests.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.5
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• pp.130-138
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• 2009

6LoWPAN is IPv6 packets transmission technology at Sensor network over the IEEE 802.15.4 Standard MAC and Physical layer. Adaptation layer between IP layer and MAC layer performs fragmentation and reassembly of packet for transmit IPv6 packets. RFC4944, IETF 6LoWPAN WG standard document define packet fragmentation and reassembly. In this paper, we propose the IRM(Immediate Retransmission Method) and SRM(Selective Retransmission Method) to manage packet fragmentation and reassembly at 6LoWPAN. Each time destination receives a fragmented packet, it sends Ack message to the source node on IRM. However, on SRM, the destination node receives all fragmented packet, it sends Ack message or Nak message to the source node. In this case, Nak message include the dropped packet number. To compare the performance of the proposed schemes, we develop a simulator using C++. The result of simulation shows the proposed schemes provider better performance than RFC4944 standard scheme.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.11
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• pp.1112-1120
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• 2008

The real-time distributed simulation at the present age concentrates on the construction of a system development environment in order to accomplish a synthetic battlefield environment connected with Live-Virtual-Constructive simulation and to realize the Simulation Based Acquisition which supports the life cycle of weapon system. Accordingly this paper describes the development environment of the UML modeling and simulation which integrates the system analysis and design methods performed during the conceptual design phase of the reconnaissance UAV system development. An integrated framework linked with the UML simulation and X-plane visualization is suggested to efficiently perform the system analysis and design, and finally the implementation contents, the analysis of experiment results and concluding remarks are described.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.379-386
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• 2011

The article is to investigate selection of Korean cuisine restaurants and levels of acculturation for foreigner living in Korea and to suggest some guidelines for drawing them and enlargement in consuming market. Out of 250 questionnaires, 220 questionnaires were used for data analysis. The findings are showed visiting for taking experience other culture and learning technology & training, not knowing well much about Korean culture, and eating experience Korean food on 30.5%, less than 2 years length in Korea. And the most difficult points are showed unclear communication, rude behavior, attitude, and language in living Korea. Second, the purpose of visiting restaurant is to spend good time with friends and to eat out special food, then foreigners usually have lunch & dinner Korean food, their own food on weekend. Third, 'service' and 'sanitation & cleanness' factors were ranked highly for foreigners living less than 2 years, but 'location' factor was ranked highly for residents living more than 4 years in the Korea. Last, foreigners living less than 2 years recognized highly on 'identification and Korea culture' in the Korea.

• Information Systems Review
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• v.6 no.1
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• pp.155-166
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• 2004

As the necessity of such mobile wireless terminals as PDAs or Cellular phones drastically increases, the terminals play important role in various business areas. In this paper, a bidding system in mobile wireless environments is constructed. However, with many mobile wireless terminals modifying at the same time their (duplicated) bidding values for a given data item, data coherency for the data item becomes essential. Therefore, in this paper, a bidding system using SyncML data synchronization mechanism is proposed and constructed. SyncML is one of data synchronization mechanisms proposed by the SyncML Initiative, a consortium of mobile wireless mobile technology leaders for universal data synchronization. The bidding system is implemented and tested in LINUX, C++, and PocketPC 2000 emulator programming environments.

• The Journal of Korean Association of Computer Education
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• v.14 no.6
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• pp.41-51
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• 2011

Informatics curriculum has been revised for informatics principles and concepts to effectively teach. According to the revised curriculum, researches are verifying the educational effects of algorithmic thinking and problem-solving abilities using programming language by applying it to various area. However, researches in programming education considering the level of student are yet incomplete. This research has analyzed the impact of the perceived level of problem solving on the performance of project completeness. As results of difference of project completeness, a high perceived level of problem solving group's performance of project completeness was higher than a low perceived level of problem solving group's one. Analysis of the impact of the perceived level of problem solving on the performance of project completeness, 'problem finding' factor had a significant impact. This research suggested the importance of 'problem finding' and self-reflecting introspective 'reviewing' stages in problem solving process using programming language.abstract of your study in English. This space is for the abstract of your study in English. This space is for the abstract of your study in English.

• Journal of Korea Multimedia Society
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• v.14 no.8
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• pp.981-991
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• 2011

MIP(Maximum Intensity Projection) is a volume rendering technique which is essential for the medical imaging system. MIP rendering based on the ray casting method produces high quality images but takes a long time. Our aim is improvement of the rendering speed using GPGPU(General-purpose computing on Graphic Process Unit) technique. In this paper, we present the ray casting algorithm based on CUDA(an acronym for Compute Unified Device Architecture) which is a programming language for GPGPU and we suggest new acceleration methods for CUDA. In detail, we propose the block based space leaping which skips unnecessary regions of volume data for CUDA, the bisection method which is a fast method to find a block edge, and the initial value estimation method which improves the probability of space leaping. Due to the proposed methods, we noticeably improve the rendering speed without image quality degradation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.4
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• pp.871-876
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• 2005

Theme park automation system is developed by using the RFID sensor reader, IIS web server, ASP.NET and MSSQL database in this paper. Its operation is that park entrance people checked automatically when he who possessed the ta8 passed the reader acquisition bound and its tag information is sent to the host computer through the RS-232 data acquisition system. Tag information and time data will be stored in the RFID database tables and reused to extract and distribute the entrance people for the purpose of each arrangement of each entertainment devices. First of all, we developed interface program between host and reader and then, programmed the related web site and database connection function using ASP.NET with $C\#$ and MSSQ. We also design and make an production of external Ant. to extend the acquisition range up to $30\~40$ cm using copper PCB plate. We confirmed the performance through the RFID test bed site.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.10a
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• pp.320-323
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• 2008

Due to the improvement of mobile device capabilities, a demand for various contents service is increasing. But the differences from heterogeneous mobile devices force to develop contents which is dependent on a mobile. To solve this problem, adaptation course that reorganize contents by the device capability is needed. In this course, device description is described using device description language but there are some problems that is absence of device description repository and the way to get device description data. In this paper, I suggest device description acquisition module and define the interfaces to access device description repository that I designed and implemented.

• The KIPS Transactions:PartD
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• v.9D no.6
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• pp.971-980
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• 2002

As the importance of knowledge management is being recognized, there is a significant amount of increase for interest in data warehousing. On-Line Analytical Processing (OLAP) systems can effectively make use of data warehouses. Although there are many commercial OLAP products, they have been developed without any kind of standard resulting in poor data exchange and difficulty in interfacing among the OLAP products. In this paper we propose an OLAP metadata interchange model that can be used among different OLAP products and have implemented an OLAP metadata interchange system that can interchange the cubes created from the metadata. XML is used for the OLAP metadata model and the user interface is Web-based, which makes it easier to interchange metadata among different OLAP products. Users can experience the different analysis environments of different products without the need to learn the complex cube creation process for each product. By extending this research to design a common query language that can be used among OLAP products, OLAP products should be able to more easily talk to one another.